EPDs: Precision Loads For Carcass Targets

We've used only high-accuracy EPD (expected progeny difference) bulls for the economically important traits since 1980, says Ashland, KS, seedstock producer Mark Gardiner. For the past 15 years or so, we've hit 90% or better Choice consistently. He adds, If any of our bull customers get below 75% Choice, they are concerned and we are concerned. Research backs up what EPDs can do, says Kansas State

He adds, “If any of our bull customers get below 75% Choice, they are concerned and we are concerned.”

Research backs up what EPDs can do, says Kansas State University (KSU) animal scientist Dan Moser.

“The EPDs for marbling, fat thickness and ribeye area do work and work very well,” he says. “Producers can feel comfortable about making the changes they need to make, even with yearling bulls with fairly low-accuracy EPDs. The low-accuracy EPDs are still more accurate than any other estimate,” he adds.

Ready to give carcass EPDs a try? Fine, but first you have to know what your feeder calves do in the carcass before you can make intelligent choices on carcass EPDs.

“I'd want to see at least two, if not three, years of carcass data on a herd,” says University of Nebraska beef cattle specialist Jim Gosey. “This needs to be on all the breeds or combinations a producer is using.”

KSU animal scientist Twig Marston agrees. “Whether using AI or natural service, making the correct genetic decision depends on the present status of the cowherd. Some herds need to emphasize red meat, others marbling, and still others a balanced combination of carcass traits.”

He continues, “Selecting the proper genetics can make great advances in calf crop value when calves are sold in the meat. But, if first you don't know where your cowherd is, the first time you put calves on a grid can become quite a crap shoot.”

Gosey also wants to know about your total marketing program. Are you feeding the cattle yourself? Are they fed as calves? Are they fed as yearlings?

If Quality Is Your Goal

If quality is your goal, think marbling. An Iowa State University (ISU) study done by grad student Mark Scott and animal scientists Doyle Wilson and Gene Rouse analyzed more than 28,000 Angus and Angus-cross cattle sired by 1,571 different Angus sires. Scott says 92% of the steers that failed to make Certified Angus Beef™ (CAB) had insufficient marbling scores.

The answer? Breed to sires with positive marbling EPDs.

“The correlation between the marbling score of the sire and the CAB acceptance rate was 0.37,” says Scott. “In all the other carcass EPDs, (fat thickness, ribeye area, hot carcass weight and percent retail product), the correlation ranged from 0.05 to -0.03.”

Scott states, “If you want to increase the CAB acceptance rate, pay more attention to a sire's marbling EPDs.”

Be forewarned, though — if your cows don't have much marbling ability, even breeding to high marbling bulls may not increase quality grade dramatically in one generation. And in cattle without the genetic potential to marble, the ISU data says there's another correlation that may get you in trouble come pay time — the one between marbling and fat thickness.

Increase marbling, and if you aren't careful, you'll increase backfat. Have you checked out the deduction for Yield Grade (YG) 4s lately? Ouch.

There's good news here, too, however. Those same CAB steers, the ones with the high marbling scores, did not have more fat cover.

Moser adds: “There are bulls with a very favorable high marbling EPD and a very favorable low fat thickness.”

So, where do you look for these bulls? Common wisdom and years of data from the U.S. Meat Animal Research Center (MARC) in Clay Center, NE, points to the British breeds.

“If you just want to work on marbling, the best opportunity to increase it would be with Angus, both black and red,” comments Gosey.

However, if you're crossbreeding with Continental bulls, don't ignore their carcass numbers — there are quality differences.

“We'll get in full pens of cattle — 60 to 100 head, and have 70% to 80% Choice, YG2,” says Robert Williams, director of breed improvement and foreign marketing for the American-International Charolais Association. “Then, we'll get in another pen and they'll run 30% Choice, YG2.”

These are primarily half-blood cattle, “but we'll get purebred heifers that are 70% to 80% Choice,” he says.

The Charolais herd book now offers carcass EPDs on marbling, carcass weight, fat thickness and ribeye area. Williams says, “These carcass EPDs allow producers to do what EPDs are supposed to do. They can make selection decisions based on how they market their cattle.”

If you're marketing through a grid that pays a bonus for Select, there isn't much need for them to select a Charolais bull on marbling, he says. If your grid pays a premium for Choice, which most do, they can select for marbling in the Charolais breed, he adds.

If Yield Is Your Goal

The Continental breeds are your best bet if you want to make strides in the red meat yield category. Focus on EPDs for ribeye area and backfat thickness. Some breeds throw in hot carcass weight and calculate a percent retail product EPD for the optimum combination of the three traits.

No matter what the official name of the trait, Gosey says if you're putting a Continental bull on British cows, you don't need to be too concerned with the exact EPD number on red meat yield.

“The average Limousin or Charolais sire will create a substantial increase in red meat yield,” he explains.

If you do want the precise carcass numbers on Continental bulls, you'll probably have to look a little harder to find them. But Gosey adds, “The Continental breeds are trying really hard. The amount of carcass data they have is much improved over the last two or three years.”

In the last four years, Williams says they've doubled the number of EPDs they offer in the Charolais breed — from five to 10. Four of those are carcass traits, while the other new EPD is scrotal circumference.

Now that you know which traits and breeds to target for quality and red meat yield, are there exact EPD numbers to shoot for? There are no easy answers on that one. In the case of marbling, however, the ISU study can provide a guideline. See Table 1 for the relationship between marbling EPDs and CAB acceptance rates.

No Good Or Bad EPDs

Still, Gardiner comments, “There are no good or bad EPDs. Each producer must figure out for himself which EPDs fit his production environment.”

“I draw on the producer's experience or data to make those decisions,” says Moser. “What are the bulls' EPDs you are currently using? How far do you need to go?”

Also, before you put all of your faith in EPDs, there are some things the numbers can't do.

“A single EPD by itself doesn't mean anything,” says University of Georgia animal scientist Keith Bertrand. “You have to compare it to something else.”

For example, say your cows are +10 lbs. for carcass weight and you breed them to a bull of the same breed who is also +10 lbs. for carcass weight. More than likely, the calves' carcass weight won't improve.

Table 1. Predicted CAB acceptance rate given marbling score EPD

Marbling EPD

Mean CAB acceptance rate

N, of 1,531 sires

-0.60

0.0%

3

-0.50

1.4%

0

-0.40

6.5%

8

-0.30

11.6%

26

-0.20

16.7%

77

-0.10

21.8%

196

0.00

26.9%

665

0.10

32.0%

307

0.20

37.1%

157

0.30

42.2%

65

0.40

47.3%

39

0.50

52.4%

19

0.60

57.5%

6

0.70

62.6%

3

Bertrand also says EPDs won't tell you exactly what your calves' carcass weight or marbling score will be, unless you have several years of experience using the same breed of sire on your cowherd. Then you can probably get close on an estimate.

Consider the environmental/management factor. Yes, carcass traits have high heritabilities, somewhere around 0.4 for marbling and maybe up to 0.5 for red meat yield. But think of the definition of heritability: the portion of variation in a trait due to the genes.

“Management on a trait like marbling still accounts for 60% of the variation,” says Gosey.

Jon Ferguson knows all too well. After using carcass EPDs since 1990, he had a pen of his Angus-Charolais cross calves harvested in '96. The heifers were 84% Choice and 87% YG1 and 2. The steers were 75% Choice and 82% YG1 and 2.

“We were dead on. We thought we had it down to a science,” Ferguson says. “Since then, we've seen those results jump all over the board, depending on the environment and where they were harvested. We've been amazed, and we've been disappointed. Their performance in the feedlot has been consistent, but we haven't been able to pinpoint where the carcass differences are coming from.”

Partly because of those curve balls thrown by the environment, producers and researchers alike warn against single-trait selection. The best red meat yield in the business isn't going to help you if your cows don't have enough body fat to get themselves through the winter and rebreed.

For instance, the Derby, KS-based consultant says, “You need to monitor carcass size. Otherwise, selection for extremes can filter back to the cowherd and ultimately impact cow size.”

“There are 18 EPD traits in the Angus sire summary,” states Gardiner. “We pay very close attention to all of them.”

Becky Mills is a beef cattle production freelance writer based in Cuthbert, GA.

Technology Speeds The Measurement Process

Thank goodness for technology. Not long ago, progeny testing was about the only way to find out what kind of carcass a sire passed on to his calves. The calves had to be fed and harvested and the carcass info collected. It was, and is, a lengthy, expensive process.

Now there's ultrasound. In the hands of a skilled operator, the technology can provide marbling, fat thickness and ribeye area measurements on a prospective sire while he's still a yearling. The same goes for his replacement-quality sisters. That data can be calculated into his or her EPDs.

“That shortens the generation interval considerably,” says Iowa State University animal scientist Gene Rouse. “It's cheaper, and you don't have the identification problems and tag transfers on the harvest floor.”

“We can capture a large amount of information at a rapid rate,” says Kansas consultant Sally Dolezal.

“As a side benefit of less cost and time, we're getting data in from a larger variety of breeders,” says Lowell Gould, genetics director for the Red Angus Association of America. “Ultrasound allows smaller breeders to take part in the carcass evaluation program. They have good genetics but have never had the chance to prove them.”

The advantages go on, especially in these days of embryo transfer. Kansas State University animal scientist Dan Moser says, “A group of full sibs are not identical. Ultrasound lets us look at which animals got the favorable draw for leanness, ribeye area and marbling.”

Kansas Angus breeder Mark Gardiner is a believer. In '98, a Gardiner yearling bull called Pinnacle went through their testing program with the rest of that year's home-breds. “He was a nice bull, but we didn't know he was remarkable,” Gardiner recalls.

At 322 days of age, he was barely old enough for an official ultrasound, but the procedure showed his marbling, ribeye and percent retail product scores were off the charts. Now, Pinnacle is the number-one bull in the breed for intra-muscular fat, in the top 1% for ribeye area and the top 2% for retail product. Ultrasound EPDs work, too.